System for cleaning a membrane

Abstract

A system ( 100 ) for cleaning a membrane ( 122 ) includes at least one of a ceramic or polymeric membrane ( 122 ) for filtering solids from fluid in a filtration system, the membrane ( 122 ) having a clean side and a dirty side. The system further comprises at least a first supply of high pressure fluid ( 132 ) with dissolved gas therein. The first supply of high pressure fluid ( 132 ) is in fluid communication with the clean side of the membrane ( 122 ) during a cleaning process. The dissolved gas in the high pressure fluid ( 132 ) is at a concentration such that gas bubbles form on the dirty side of the membrane ( 122 ) during the cleaning process, wherein dissolved gas includes a first gas and the first gas is an oxidative gas.

1 . A system ( 100 ;  200 ;  300 ) for cleaning a membrane ( 122 ;  322 ), wherein the membrane ( 122 ;  322 ) includes at least one of a ceramic or polymeric membrane for filtering solids from fluid in a filtration system, the membrane having a clean side ( 124 ;  321 ) and a dirty side ( 126 ;  323 ); the system further comprising at least a first supply of high pressure fluid ( 132 ;  232 ,  332 ) with dissolved gas therein; the first supply of high pressure fluid ( 132 ;  232 ,  332 ) being in fluid communication with the clean side ( 124 ;  321 ) of the membrane ( 122 ;  322 ) during a cleaning process; and the dissolved gas in the high pressure fluid ( 132 ;  232 ,  332 ) being at a concentration such that gas releases, optionally in the form of bubbles, on the dirty side ( 126 ;  323 ) of the membrane ( 122 ;  322 ) during the cleaning process; wherein the dissolved gas includes a first gas and the first gas is an oxidative gas. 
     
     
         2 . The system ( 200 ;  300 ) as recited in  claim 1 , further comprising a source of cleaning reagent ( 220 ;  325 ) being selected to physically or chemically coact with the dirt accumulated at the membrane ( 122 ;  322 ) during the cleaning process. 
     
     
         3 . The system ( 100 ;  200 ) as recited in any one of the preceding claims, comprising a second supply of high pressure fluid ( 142 ;  242 ) being selectively in fluid communication with the membrane ( 122 ), the second supply of high pressure fluid ( 142 ;  242 ) having low concentration of dissolved gas therein. 
     
     
         4 . The system ( 100 ;  200 ;  300 ) as recited in any one of the preceding claims, wherein the first supply of high pressure fluid ( 132 ;  232 ;  332 ) with dissolved gas has a dissolved gas concentration greater than about 50% of solubility at high pressure conditions. 
     
     
         5 . The system ( 100 ) as recited in any one of the preceding claims, further comprising a separation tank ( 180 ), the separation tank ( 180 ) downstream of the membrane ( 122 ) in a reverse flow path ( 104 ). 
     
     
         6 . The system as recited in any one of the preceding claims, further comprising a transition control allowing for transition from the first supply of high pressure fluid to the second supply of high pressure fluid. 
     
     
         7 . A method for cleaning a membrane ( 122 ;  322 ), the method comprising:
 dissolving an oxidative gas into a first fluid in a first vessel ( 130 ;  230 ;  330 ) at a concentration in excess of the maximum solubility of the dissolved oxidative gas at an operating pressure present on a dirty side ( 126 ;  323 ) of the membrane ( 122 ,  322 ) during a cleaning process; during the cleaning process, supplying the first fluid to a clean side ( 124 ;  321 ) of the membrane ( 122 ;  322 ) such that it passes through the membrane ( 122 ,  322 ) and oxidative gas releases, optionally in the form of bubbles, on the dirty side ( 126 ;  323 ) of the membrane ( 122 ;  322 ).   
     
     
         8 . The method as recited in  claim 7 , further comprising introducing a second fluid with low amounts of dissolved gas through the membrane ( 122 ;  322 ), and at least partially replacing the first fluid. 
     
     
         9 . The method as recited in any one of  claims 7  and  8 , wherein cleaning the membrane ( 122 ;  322 ) with the bubbles includes scouring the membrane ( 122 ;  322 ) with the bubbles. 
     
     
         10 . The method as recited in any one of  claims 7  to  9 , further comprising sending the fluid to a separation tank ( 180 ) after cleaning the membrane ( 122 ), and floating dirt particles with attached gas and separating clean fluid from the dirt particles. 
     
     
         11 . The method as recited in any one of  claims 7  to  10 , further comprising introducing a feed of coagulant chemicals including one or more of inorganic salts, organic polyelectrolyte chemicals. 
     
     
         12 . The method as recited in any one of  claims 7  to  11 , further comprising recycling the fluid to an inlet near the membrane. 
     
     
         13 . The method as recited in any one of  claims 7  to  12 , further comprising introducing one or more of low pressure ozone or ionized air, or pressurized gas with ozone, or pressurized ozone to the membrane ( 322 ). 
     
     
         14 . The method according to any one of  claims 7  to  13 , comprising pressurizing the first fluid and/or the second fluid, respectively.